Year 8 Science: Body Systems

• Year 8 Science: Body Systems Revision Booklet

Hot Tips List

• The major body systems are circulatory and respiratory, and it's important to know their functions.
• Key organs' structure and function within the circulatory and respiratory systems should be examined.
• The relationship between the circulatory and respiratory systems in oxygen and carbon dioxide transport should be described.
• The role of the heart, blood vessels, and blood in circulation should be recognized.
• You should identify and explain the function of different blood vessels (arteries, veins, capillaries).
• Gas exchange in the lungs and the role of alveoli needs to be understood.
• You should investigate how lifestyle factors (e.g., diet, exercise, smoking) affect heart and lung health.
• Data related to heart rate, blood pressure, and respiration rate under different conditions should be interpreted.
• It's important to analyze the impact of diseases (e.g., atherosclerosis) on body system function.
• A good understanding of scientific variables (independent, dependent, and controlled) and their application to science experiments is important.

Circulatory System

• Blood circulates throughout the body in about one to two minutes.
• The heart/ventricles are the pump in the circulatory system.
• Capillaries are the smallest type of blood vessel.
• Arteries are the most elastic type of blood vessel.
• Valves stop blood from flowing backwards in veins.
• The lungs are where blood becomes oxygenated.
• The aorta is the large vessel carrying blood out of the heart.
• Red blood cells carry oxygen from the lungs to the body's cells.
• White blood cells act as soldiers around the body.
• Arteries are vessels that carry blood away from the heart.
• Veins are vessels that carry blood back to the heart.
• The heart pumps blood around the body in a continuous, closed cycle.
• The carotid artery carries blood to the head.
• The jugular vein returns blood from the head.
• The circulatory system is not made up of veins only.
• Muscles are involved in controlling the flow of blood.
• Blood is the fluid which circulates in the body.
• Organs the blood passes through, starting at the aorta, are: heart, kidneys, small intestine, large intestine, liver, stomach, pancreas, reproductive organs/pelvis, leg muscles.
• In the intestines, the blood delivers oxygen for respiration and metabolism, and it absorbs nutrients.
• In the lungs, the blood picks up oxygen and delivers carbon dioxide.

Heart

• The right atrium is the chamber where deoxygenated blood enters.
• The pulmonary artery carries blood to the lungs.
• The left ventricle is the chamber that has blood at the highest pressure.
• The aorta is the largest blood vessel, delivering blood to the body.
• Blood leaves the heart through arteries.
• Arteries have elastic walls.
• The smallest blood vessels are capillaries.
• Blood returns to the heart through veins.
• Veins have non-elastic walls.

Respiratory System

• Respiration is a series of chemical changes that release energy in the cells.
• Exhaling is breathing out.
• Inhaling is breathing in.
• The diaphragm is the sheet of muscle that controls breathing.
• The word equation for respiration: oxygen + glucose → water + carbon dioxide + energy.
• Reactants in respiration are oxygen and glucose.
• Products of respiration are water and carbon dioxide.
• Air travels through the respiratory system in this order when breathed out: alveoli, bronchioles, bronchus, trachea, mouth, and nose.
• The respiratory system takes in air, extracts oxygen and absorbs it into the blood, removes carbon dioxide from the blood and expels it with unused air.
• Cilia trap dust and bacteria.
• Alveoli allow the exchange of gases between the air and the blood.
• Lungs work far better with alveoli increase surface area.
• Breathing rate increases as you start to run and increases more as you start to run faster and then it will slow as you stop running.
• Air enters the body in the following order through the respiratory system: Nasal cavity, epiglottis, pharynx, bronchi, larynx/trachea, bronchioles and alveoli

Breathing

• Inhalation is when we take in air.
• Exhalation is when we pass out air.
• During inhalation, the intercostal muscles between the ribs contract, moving the ribs up and out.
• The diaphragm muscle contracts, moving down.
• The volume of air inside the chest increases, decreasing the pressure inside the lungs.
• Air enters the lungs because the air pressure outside the chest is higher than the pressure inside the lungs.
• During exhalation, the intercostal muscles relax, causing the ribs to move down and in.
• The diaphragm muscle relaxes and moves up.
• The volume of air inside the chest decreases, increasing the pressure inside the lungs.
• Air leaves the lungs because the air pressure outside the chest is lower than the pressure inside the lungs.

Circulatory System

• Angina is severe chest pain caused by lack of oxygen to the heart muscle.
• Plaque is a deposit of calcium, cholesterol, and fibrin on artery walls, reducing blood flow.
• Hemoglobin is an iron-containing chemical in blood that carries oxygen, giving blood its red color.
• The septum separates the two sides of the heart.
• The atrium is a heart chamber that acts as an entry for blood.
• Plasma is the main component of blood.
• The system move nutrients/oxygen to the cells, remove wastes (carbon dioxide), and distribute heat.
• The regular expansions and contractions of the arteries in response to heartbeat is the pulse.
• Bruise is caused by capillaries bursting because of a knock or some injury and blood leaking into the surrounding tissues.
• Deep Vein Thrombosis (DVT) is caused by blood pooling in deep veins in the legs.
• Blood is pumped around the body, transporting nutrients, waste, and heat.
• Capillaries' walls are only one cell thick and close to every cell.
• The heart is oriented in drawings as if looking at someone else's heart, reversing left and right.
• Valves control blood flow, preventing backflow.
• Arteries carry blood away from the heart.
• Cardiac muscles are muscle that do not get tired.
• Arteries have thick walls.
• Red blood cells are smaller and far more numerous than white blood cells.
• Red blood cells contain hemoglobin, which carries oxygen.
• White blood cells circle and destroy bacteria and some viruses.
• Veins carry deoxygenated blood back to the heart (lungs).
• Deoxygenated blood contains carbon dioxide, pressure prevents it from getting to the lungs.

Multiple Choice Questions

• Arteries carry blood away from the heart.
• After passing through the pulmonary vein, blood goes into the left atrium.
• Normally oxygenated blood is in structure D,E, A and C.
• Red blood cells in blood carries the oxygen to the body.

Photosynthesis

• The direction taken by most of the water absorbed by plants is; W, Y, Z